Missing one triangle

[zuffik]

Hey I'm trying to make low poly rocks in UE5 with random points generated and convex hull calculated around them. Everything works perfectly except that it always generate one triangle less (see picture below).

In code I just take all the vertices generated in BluePrint (UE5 procedural language), populate them into point cloud (as described in readme) and remap back to structure that I use to describe triangles. It happens with any seed. The vertices of empty triangle seem to have random indexes. So far I can work with that by rotating a rock that the empty triangle faces the ground but can be frustrating for future users.

Attachments

Code

#include "ConvexHullGenerator.h"
#include "LowPolyGame/External/QuickHull/QuickHull.hpp"

TArray<FIntVector>& UConvexHullGenerator::CalculateConvexHull(TArray<FVector>& Vertices)
{
    quickhull::QuickHull<float> qh;
    std::vector<quickhull::Vector3<float>> PointCloud;
    for (const auto Vertex : Vertices)
    {
        quickhull::Vector3<float> V3(Vertex.X, Vertex.Y, Vertex.Z);
        PointCloud.push_back(V3);
    }
    auto Hull = qh.getConvexHull(PointCloud, true, true);

    const auto Result = new TArray<FIntVector>();
    const auto IndexBuffer = Hull.getIndexBuffer();
    float Buffer[3];
    for (int i = 0; i < IndexBuffer.size(); i++)
    {
        if (i > 0 && i % 3 == 0)
        {
            FIntVector Vector = FIntVector(Buffer[0], Buffer[1], Buffer[2]);
            Result->Add(Vector);
        }
        Buffer[i % 3] = IndexBuffer[i];
    }

    return *Result;
}

Preview